Poland's post-consumer PET is 8-9 kton/year, ca. 10% of overall annual polymer wastes. Flaked PET, bulk d., 0.3 Mg/m(3), intrinsic viscosity [eta] = 0.78-0.81 dL/g, was heated 0.5 h to 130-145degreesC, kept so for 3.5 h, and regranulated cold in a co-rotating twin-screw extruder to study regranulate's [eta] in relation to configuration (A or B) of plastication system, screws speed (140, 160 or 240 rpm), and degassing parameters. The B had no transporting-and-choking segments before degassing section 1 and had more (than the A) mixing-and-kneading segments in mixing zone 2 before degassing section 2. The extruder had two degassing sections, 10 and 60 kPa. The regranulated PET revealed (DSC) two T-g-values, 66.97 and 78.49degreesC, attributable to two fractions differing in M. The advisable speeds for 70-mm screws were 140-160 rpm. Throughput was 210-240 kg PET/h, channel and head temps., 210-245 and 250-270degreesC, resp., energy consumed 0.15-0.17 kWh/kg, and [eta] 0.68-0.79. The length of the first plastication zone and the type of the transporting-and-choking segments were crucial for the quality and for the [eta] (> 0.76) of the regranulated PET.